Criminal procedure is the only way to enforce criminal law. Balance is one of the main component of criminal procedure. It brings balance to criminal law because ultimate ends of criminal laws can be dual and ambiguous. Criminal justice process has several steps. Crime detection steps consist of both, active and proactive strategies. When there is a one suspect the investigation enters into accusatory stage. When suspects of the police get some proofs investigation passes to arrest stage. Search stage comes after the arrest stage. In some cases search stage can proceed arrest. Booking stage completes the actions of the police. Next group of steps describes criminal prosecution. This stage starts after police passes the case to prosecutors. On the charging stage prosecutors decide if any crime has been committed. If they decide to charge, they pass to the next stage called complaint stage. Adjudication stages goes the next. Formal court proceedings take place in court. Formal proceedings consist of first appearance, preliminary hearings, arraignment, pretrial motions, and trial, the final part of court proceedings. Sentencing steps come after court proceedings. On this stage judge and jury give official judgment of the crime committed. In some cases appeal steps can follow sentencing steps. Appeal steps consist of attacks of conviction in order to prove innocence of the convict. Punishment steps constitute the last phase of criminal process.
Evidence is a proof, which can be used in judicial proceedings. Evidence can be physical, documentary, digital, exculpatory, scientific, demonstrative or testimony. Evidence can be direct on circumstantial. Under circumstantial evidence we usually understand indirect evidence, which implies the existence of some fact but does not prove its existence directly. Usually this evidence is achieved in the process of probable reasoning. Evidence must conform to certain rules in order to be recognized by the court. First of all it must be relevant. It means that evidence must help the proceeding. But there are cases when even relevant evidence cannot be used in the circumstances. This happens in the cases when relevant evidence is prejudicial, cumulative of confusing. Some social policies can also prevent from the use of relevant evidence. For example, the use of evidence of liability insurance is limited because it can discourage the parties to carry insurance. The use of evidence of subsequent remedial measures is limited because it can discourage parities from fixing hazardous conditions. The use of plea negations evidence can be limited because it prevents parties from pleading guilty.
The American system of evidentiary rules is one of the most complicated in the world. In English judiciary system almost all evidence by the proofed by witnesses.
Under wittiness we usually assume a person, who testifies in court under oath. Wittiness is a person, who possesses some knowledge about the issue, which has some connection to proceedings. The expert witness is defined as a witness, who has special knowledge of the subject about which he is to testify.
Such a definition implies that expert witness possesses more knowledge than an average person does. The expert witness can give special assistance to the court. Experience of expert wittiness can come either from education or experience. The court must qualify wittiness before he or she is recognized as an expert witness. For this purposes,, he or she must provide testimony of his or her special training, which proves the possession of special knowledge, skills of experience. Testimony, given by the expert witness is usually recognized as expert testimony. Expert witnesses can be asked a hypothetical question if these questions belong to the areas of their knowledge.
The judge or the tribunal can turn to the help of expert witnesses with the request to evaluate certain fact or give court additional knowledge on the judging issue. Expert witness has the right to give legal expertise of fact or action. In many countries perjury, committed by expert witnesses is punished severally.
All witnesses, who are not testifying as expert witness belong to the category of lay witnesses. Lay witnesses usually do not testify in the form of opinion. Still, there are cases when lay witnesses are able to testify in the form of an opinion. In these cases the testimony is either based on the perceptions of witness or helps to understand his other testimonies. There are cases when a person can be both lay and expert witness. Under lay expert witness we understand a person, whose expertise or special competence derives from experience in a field of endeavor rather than from studies or diplomas.